Section Modulus Calculator
Calculate section modulus for common cross-sections.
This tool is for informational and educational purposes only. It is not a substitute for professional financial, medical, legal, or engineering advice. See Terms of Service.
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Request a ToolHow to Use the Section Modulus Calculator
Select a cross-section shape and enter dimensions.
- Choose shape. Rectangle, circle, hollow circle, or I-beam.
- Enter dimensions.
- Read the result in m3.
About the Section Modulus Calculator
The section modulus is a geometric property of a cross-section that measures its resistance to bending. It equals the moment of inertia divided by the distance from the neutral axis to the extreme fiber (S = I/c). A larger section modulus means a beam can resist higher bending moments. Engineers use this property to select appropriate beam sizes for structural applications.
Frequently Asked Questions
What is the difference between elastic and plastic section modulus?
Elastic section modulus (S) is used for allowable stress design. Plastic section modulus (Z) accounts for full plastification of the cross-section and is always larger. Z is used in plastic design.
Which shape is most efficient for bending?
I-beams are most efficient because they concentrate material at the flanges, far from the neutral axis, maximizing the moment of inertia and section modulus for a given weight.
How does doubling the height affect section modulus?
For a rectangle, doubling the height quadruples the section modulus because S = bh^2/6 and h is squared.